If you only need D.Rings for your own(ex: 2 pcs), just your sniper.
If you plan on farming D.Rings for a living, start learning how to use star gladiator.
By change of stats what i meant was applying the basic stat bonuses,
for example 99+27 dex of yours, compared to 93+27 or 99+21 dex, will be almost the same. Damage difference won't be noticeable.
You could change valk helm to ulle's cap to save stats, put nightmare or something.
after restating, use your full buff and add dex first, then add agi slowly till you get the last possible bonus aspd.
example, you have 189 aspd at 90 agi. Put agi stats carefully till your aspd reaches 190, meaning it doesn't need to be 99 agi at all.
I'll try to post a ss of my farm build 190 aspd sniper a little bit later
EDIT: There ya go.
Note: Luck isn't needed, I just added it there for a fancy auto blitz with my lazy 190 aspd build and for critical hits too.
You can put them in int for sp or vit for hp, maybe str for fly wings arrows and such.
Ixion's Wings is my universal bow, use any bow you like.